An embodiment method of detecting an arc fault includes communicating a power line signal, including a communication signal modulated on an alternating current power signal, over a power line. The communication signal is communicated according to a power line network protocol. A power spectrum of the communication signal includes a first frequency band and a second frequency band different from the first frequency band. In accordance with the power line network protocol, a power of the communication signal in the first frequency band is attenuated in comparison to the power of the communication signal in the second frequency band. The method further includes performing arc fault detection on the spectral portions of the power line signal that are within the first frequency band.